Transient analytical modeling of the observed behavior in a scaled-down physical slope model under failure event induced by artificial precipitation
Unsaturated soils; Slope Stability; Transient Flow; Precipitation; Probability of Failure
The interaction between soil dynamics and the atmosphere represents a significant challenge and an area of increasing interest in geotechnical engineering. This dissertation focuses on modeling the behavior of unsaturated slopes subjected to intense precipitation events, exploring the applicability of analytical models. The theoretical foundation includes Darcy's Law and the Richards Equation, supplemented by recent advances in modeling flows in unsaturated soils, as exemplified by the approach of Cavalcante & Zornberg (2017). The study assesses the accuracy of these models in predicting the transient behavior of unsaturated slopes, validating the predictions with experimental data obtained from a scaled model of a slope. This process involves understanding how variations in the internal energy of fluids, hydraulic conductivity, and the soil-water retention curve influence water movement and, consequently, the stability of slopes. The dissertation explores the application of a probabilistic approach to assess the stability of unsaturated slopes, employing the Rosenblueth Point Estimate Method (PEM) implemented in the Wolfram Mathematica software. The analysis focuses on determining the transient failure probability and the reliability index, incorporating random variables such as dry unit weight, hydraulic conductivity, the hydraulic adjustment parameter, and the soil's effective friction angle. Sixteen simulations were conducted, considering the random variables and their distributions to estimate the safety factor under various precipitation and humidity conditions, calculating the failure probability for different tests and depths. This methodology allowed for identifying critical moments of increased failure probability, emphasizing the importance of initial moisture conditions and the effects of preceding rainfall.